Non-volatile graphene-drum memory chip

ABSTRACT

The present invention relates to non-volatile memory chips having graphene drums. In some embodiments, the non-volatile memory chips have one or more layers that each includes a plurality of graphene-drum memory chip cells.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority to: provisional U.S. Patent ApplicationSer. No. 61/391,727, filed on Oct. 11, 2010, entitled “Non-VolatileGraphene Drum Memory Chip,” which provisional patent application is eachcommonly assigned to the Assignee of the present invention and is herebyincorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

The present invention relates to non-volatile memory chips havinggraphene drums.

SUMMARY OF THE INVENTION

Graphene membranes (also otherwise referred to as “graphene drums”) havebeen manufactured using process such as disclosed in Lee et al. Science,2008, 321, 385-388. PCT Patent Appl. No. PCT/US09/59266 (Pinkerton) (the“PCT US09/59366 Application”) described tunneling current switchassemblies having graphene drums (which graphene drums generally havinga diameter between about 500 nm and about 1500 nm). As described in thePCT US09/59366 Application, which is attached hereto at Appendix A, thegraphene drum is capable of completely sealing the chamber formed by thegraphene drum (i.e., the graphene drum provides a complete seal tofluids inside and outside the chamber). U.S. Patent Appl. No. 61/301,209(Pinkerton) (“the '209 Application) described pump and engine systemshaving graphene drum. The '209 Application is attached hereto atAttachment B.

In embodiments of the present invention, graphene drums are employed ina non-volatile memory chip, i.e. a graphene-drum memory chip (“GDMC”).

Advantages of utilizing graphene drums in a memory chip include:

-   -   a. The GDMC can have many active layers. This is because the        GDMC does not require the pure silicon at the bottom of the chip        like current flash devices.    -   b. Many memory elements can share the same input/output wiring.        This is because each graphene drum within a cell has a unique        mechanical resonant frequency that can be addressed by driving        the entire cell with an electrical frequency that matches this        mechanical frequency.    -   c. Each cell (which might contain 1000 graphene drums) can be        addressed with just four input/output pins per layer. This can        be done by selecting a unique row and column by matching the        electrical input to the mechanical resonant frequency of a        graphene drum that connects to a given row/column.    -   d. The graphene drum memory chip requires less power to        read/write than flash memory because it takes less voltage        (typically less than 1 volt) to read/write an array of graphene        drums.    -   e. The power demand of the memory chip is reduced because many        graphene drums within a given array can be read simultaneously        by applying a DC voltage and making use of the thermal        vibrations of each graphene drum (instead of driving each        graphene drum with an AC signal).    -   f. The device will have a high read speed because many graphene        drums within a cell can be read simultaneously.    -   g. The state of each graphene drum within an array can be        rapidly changed by scrolling through a range of resonant        frequencies with a voltage signal on a nearby trace.

These advantages yield a very high memory density of at least oneterabyte per square centimeter (using a relatively conservative 90nanometer feature size) and low cost per gigabyte (since the device canuse lower cost “old” foundries and the gigabyte per mass of material islow).

As used herein, a “graphene-drum memory chip” (or “GDMC”) is a memorychip that utilizes one or more graphene drums (such as a memory chipthat utilizes an array of graphene drums). A “graphene-drum memory chipcell” is a cell of a memory chip that utilizes one or more graphenedrums. A “graphene-drum memory chip layer” is a layer of a memory chipthat utilizes one or more graphene drums.

Alternatively, other types of electrically conductive membranes (alsoreferred to as “electrically conductive drums”) may be utilized in lieuof graphene membranes in embodiments of the present invention, such as,for example, graphene oxide membranes.

In general, in one aspect, the invention features a memory chip thatincludes an array of electrically conductive drums that have a range ofmechanical resonant frequencies that can be individually addressed withan electrical signal between said electrically conductive drums and anearby electrically conductive member.

Implementations of the invention can include one or more of thefollowing features:

The array of electrically conductive drums can be an array of graphenedrums.

The memory chip can include a layer. The layer can include the array ofgraphene drums.

The layer can include a plurality of graphene drum memory chip cells.Each of the graphene drum memory chip cells can include at least onegraphene drum.

The memory chip can further include a selection trace system. Theselection trace system can include a plurality of selection traces. Eachof the graphene memory chip cells can be operably connected to acorresponding pair of selection traces in the selection traces such thateach of the graphene memory chip cells can be individually selected byselecting the corresponding pair of selection traces for thegraphene-drum memory chip cell.

Each of the graphene drums in the plurality of graphene-drum memory chipcells can be operable to be in an “on” position and an “off” position.

The memory chip can further include a contact trace system. The contacttrace system can include at least one contact trace. A graphene drum inthe plurality of graphene-drum memory chip cells is in a first positionwhen the graphene drum is contacting at least one of the contact tracesin the contact trace system. The graphene drum in the plurality ofgraphene-drum memory chip cells is in a second position when thegraphene drum is not contacting at least one of the contact traces inthe contact trace system. The first position and the second position areeither (a) the “on” position and the “off” position, respectively, or(b) the “off” position and the “on” position; respectively.

The memory chip further includes a voltage source and an externalcircuitry. The voltage source can be operable to apply a voltage suchthat the external circuitry can determine whether the graphene drummemory chip cell of the plurality of graphene-drum memory chip cells isin the “on” or “off” position.

The memory chip can further include a high voltage source. The highvoltage source that can be operable to apply a pulse individually to thegraphene drum in the graphene memory chip cells to switch the graphenedrum from the “on” position to the “off” position.

The memory chip can further include a trace system. The trace system caninclude at least a first trace and a second trace. A graphene drum inthe plurality of graphene-drum memory chip cells can be in the “on”position when the graphene drum is in a stable equilibrium between thevan der Waals forces caused by the first trace and a mechanicalrestoration force. The graphene drum in the plurality of graphene-drummemory chip cells can be in the “off” position when the graphene drum isin a stable equilibrium between the van der Waals forces caused by thesecond trace and the mechanical restoration force.

The graphene drum does not need to contact the first trace when in thefirst position. The graphene drum does not need to contact the secondtrace when in the second position.

The graphene drum can be operable to receive a voltage such that athermal amplitude of the graphene drum can cause an AC tunneling currentthat can be detected to determine whether the graphene drum is in the“on” position or the “off” position.

The memory chip can further include a trace system having at least afirst trace and a second trace. The first trace can be in contact with afirst layer of oxide positioned between the first trace and the graphenedrum. The first layer of oxide can be in contact with a first layer ofmetal positioned between the first layer of oxide and the graphene drum.

A graphene drum in the plurality of graphene-drum memory chip cells canbe in a first position when the graphene drum is contacting the firstlayer of metal. The graphene drum in the plurality of graphene-drummemory chip cells can be in a second position when the graphene drum isnot contacting the first layer of metal. The first position and secondposition can be (a) the “on” position and the “off” position,respectively, or (b) the “off” position and the “on” position,respectively.

The second trace can be contacted with a second layer of oxidepositioned between the second trace and the graphene drum. The secondlayer of oxide can be contacted with a second layer of metal positionedbetween the second layer of oxide and the graphene drum.

The memory chip can have a plurality of layers. Each layer of theplurality layers can include an array of graphene drums. Each layer ofthe plurality layers can include a plurality of graphene-drum memorychip cells. Each of the graphene-drum memory chip cells can include atleast one graphene drum of the plurality of graphene drums.

Some of the electrically conductive drums of the memory chip can haveparticles of material on one side. The electrically conductive drumsthat have particles can have an altered resonant frequency due to theparticles there upon.

The particles of material can be balls of materials.

The electrically conductive drums can be graphene drums.

The material of the particles can be a metal.

The particles can be particles of sputtered metal.

The amount of alteration of the resonant frequency of the electricallyconductive drums can depend on the number, size, and location of theparticles upon the electrically drums.

The memory chip can further include a trace system having at least afirst trace and a second trace. The first trace can be in contact of atleast one non-conductive feature positioned between the first trace andthe graphene drum.

The non-conductive feature can be an oxide feature.

A graphene drum in the plurality of graphene-drum memory chip cells canbe in a first position in which the graphene drum is contacting thenon-conductive feature when the graphene drum is in the first position.The graphene drum in the plurality of graphene-drum memory chip cellscan be in a second position in which the graphene drum is not contactingthe non-conductive feature when the graphene drum is in the secondposition. The first position and second position can be (a) the “on”position and the “off” position, respectively, or (b) the “off” positionand the “on” position, respectively.

The particles are operable for enabling a field emission current to flowbetween the graphene drum and the second trace.

In general, in another aspect, the invention features a method ofreading a memory state of an electrically conductive drum in anelectrically conductive memory chip cell. The electrically conductivedrum is operable for moving between a first position and a secondposition. The method includes applying a voltage between theelectrically conductive drum and a nearby electrically conductive memberthat can cause a tunneling current due to the thermal amplitude of thegraphene drum. The method further includes sensing the frequency of thetunneling current. The method further includes determining whether theelectrically conductive drum is in the first position or the secondposition. The first position and second position are (a) the “on”position and the “off” position, respectively, or (b) the “off” positionand the “on” position, respectively.

Implementations of the invention can include one or more of thefollowing feature

The electrically conductive drum can be a graphene drum.

The electrically conductive drum can be in a first position in which theelectrically conductive drum is contacting the electrically conductivemember when the electrically conductive drum is in the first position.The electrically conductive drum can be in a second position in whichthe electrically conductive drum is not contacting the electricallyconductive member when the electrically conductive drum is in the secondposition.

The second position can be a stable equilibrium position where van derWaals forces are balanced with mechanical restoration forces upon theelectrically conductive drum when positioned at the second position.

The electrically conductive drum can be in a first position in which theelectrically conductive drum is not contacting the electricallyconductive member when the electrically conductive drum is in the firstposition. The electrically conductive drum can be in a second positionin which the electrically conductive drum is not contacting theelectrically conductive member when the electrically conductive drum isin the second position.

The first position can be a first stable equilibrium position where vander Waals forces are balanced with mechanical restoration forces uponthe electrically conductive drum when positioned at the first position.The second position can be another stable equilibrium position where thevan der Waals forces are balanced with the mechanical restoration forcesupon the electrically conductive drum when positioned at the secondposition.

The electrically conductive member can be in contact with a first layerof oxide positioned between the electrically conductive member and theelectrically conductive drum. The first layer of oxide can be in contactwith a first layer of metal positioned between the first layer of oxideand the electrically conductive drum.

The electrically conductive drum can be in a first position when theelectrically conductive drum is contacting the first layer of metal whenthe electrically conductive drum is in the first position. Theelectrically conductive drum can be in the second position when theelectrically conductive drum is not contacting the first layer of metalwhen the electrically conductive drum is in the second position.

A second electrically conductive member nearby the electricallyconductive drum can be contacted with a second layer of oxide positionedbetween the second electrically conductive member and the electricallyconductive drum. The second layer of oxide can be contacted with asecond layer of metal positioned between the second layer of oxide andthe electrically conductive drum.

The method can further include selecting the electrically conductivedrum using a selection trace system operatively connected to theelectrically conductive drum memory chip cell. The selection tracesystem can include a plurality of selection traces. The electricallyconductive drum memory chip cell can be operably connected to acorresponding pair of selection traces in the selection traces such thatthe electrically conductive memory chip cell can be individuallyselected by selecting the corresponding pair of selection traces for theelectrically conductive drum memory chip cell.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofmay be better understood, and in order that the present contribution tothe art may be better appreciated. There are additional features of theinvention that will be described hereinafter.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of the description and should not beregarded as limiting.

DESCRIPTION OF DRAWINGS

FIG. 1 depicts a cutaway view of a single graphene-drum memory chiplayer of a graphene-drum memory chip.

FIG. 2 depicts a detailed view illustrating how three graphene-drumlayers can be stacked in a graphene-drum memory chip.

FIG. 3 depicts the stacked graphene-drum memory chip of FIG. 2.

FIG. 4 depicts an embodiment of the present invention in which thegraphene-drum memory chip has graphene drums whose reasonant frequencyhas been altered by the addition of small balls of material on a side ofthe graphene drums.

FIGS. 5A-5D depict several graphene-drum memory chip cells of thepresent invention.

FIG. 6 depicts an embodiment of the present invention in which thegraphene-drum memory chip has a voltage placed between the graphene anda trace.

DETAILED DESCRIPTION

In an embodiment of the present invention, one or more graphene drumscan be utilized in a graphene-drum memory chip. FIG. 1 depicts a cutawayview of a single graphene-drum memory chip layer 101 of a graphene-drummemory chip.

The small drum traces on the left and top of the chip (selection traces102 and 103) are used to select a given row or column of the device. Forexample, to access the center cell (cell 104, which contains fourgraphene drums), one would apply an AC signal with a DC component (viatwo pins, one of which (pin 105) is visible in first figure) to theupper and lower layers of the left selection trace (selection trace 102)that matches the mechanical resonant frequency of the middle graphenedrum pair 106 (pair is for redundancy). These two redundant graphenedrums would then vibrate up/down until they contacted a middle tracewhich is electrically connected to the middle row in figure. The DCcomponent would help the graphene drums to pull down toward theconductive trace and also help the graphene drum stay engaged with theconductive trace once contact is made.

Applying another AC (with a DC component) signal between the upper andlower layers of the top selection trace (selection trace 103) thatmatches the mechanical resonant frequency of the middle graphene drumpair 1-7 vibrates these drums up/down until they contacted a middletrace (which is electrically connected to the middle column) in figure.At this point, the upper left selection trace 102 is electricallyconnected to the middle row and the upper top selection trace 103 iselectrically connected to the middle column. The four larger graphenedrums (in cell 104) that have the active row and column are the“graphene-drum memory chip cell.”

To read the memory state (on or off) of each graphene drum within acell, an AC voltage is applied to the two selection traces at afrequency that matches a given graphene drum within a cell. If thegraphene drum is free (not stuck down to a column trace), it willresonate and create an AC tunneling current that can be sensed as “off”by external circuitry (not shown); if the drum is stuck down to thecolumn trace (which is a metallic trace with a thin layer of oxide onits surface to prevent large currents) via attractive van der Waalssurface forces it will not generate an AC tunneling current and will beconsidered “on.” A range of frequencies are applied to the cell untileach graphene drum within the cell is found to be on or off. Oncefinished, the DC component applied to each selection trace is turned offand the graphene drums of the selection traces disengage. The processcan then be repeated to read the stated of other graphene drums withinother cells using the same process.

A resonating graphene drum will have a significant variation incapacitance over its range of travel that will also create a uniquecurrent response at the resonant frequency that can be used to sense thestate of a graphene drum, even if tunneling current does not occur.

Another method to read the memory state of all the graphene drums withina cell simultaneously is to apply a voltage signal that contains asuperposition of all of the resonant frequencies of the graphene drums.The resulting current signal can be then be parsed for individual drumresponses using a set of bandpass filters, or any other suitable methodof time domain or frequency domain signal processing, either with analogor digital electronics.

To change the state of graphene drums within a give cell, a relativelyhigh voltage pulse of the same polarity is applied to a given column androw trace, resulting in an electrostatic repulsion that frees anygraphene drum that was adhered to the column trace. At this point, an ACsignal can be applied to the row and column traces (via the selectiontraces) that has a frequency that matches the mechanical frequency of agiven graphene drum, forcing the graphene drum to resonate until itcontacts and adheres to the column trace. A different AC frequency canbe used to make a different graphene drum within a cell adhere to thecolumn trace.

FIG. 2 depicts a detailed view illustrating how three graphene-drumlayers can be stacked in a graphene-drum memory chip, and FIG. 3 depictsthis stacked graphene-drum memory chip. As can be seen in FIGS. 2-3, itis possible to stack many layers (three layers 202, 203, and 204 areshown) together to achieve very high storage per unit area. Layer 204 isshown in detail illustrating the graphene sheet 210 (having the graphenedrums), the metal sheets 209 and 207, and oxide sheet 208. Each oflayers 202, 203, and 204 has four via pins that make their way to thebottom of the chip 206 for easy access to a circuit board. For example,Layer 202 has pins 205 a, 205 b, 205 c, and 205 d.

FIG. 4 depicts a graphene-drum memory chip 401 that has graphene drums402 whose resonant frequency has been altered by the addition of smallballs 403 of material on a side of the graphene drums. Such balls ofmaterial can be made of metal. Such balls can be added by a sputteringprocess, which can be designed to control the number, size, and locationof the balls. The number, size, and location of the balls on thegraphene drum will alter the resonant frequency of the graphene drum.

FIG. 5A depicts a graphene-drum memory chip cell 501 that does notrequire the graphene drum to physically contact with the metal traces.As shown in the graphene-drum memory chip cell 501 of FIG. 5A, a smallgraphene drum 502 (such as a 5-100 nanometer diameter graphene drum) canmove up toward trace 503 (as illustrated in the first position “a” ofgraphene drum 502 shown by the solid line) or down toward trace 504 (asillustrated in the second position “b” of graphene drum 502 shown by thedashed line). When the graphene drums are this small, there can be astable equilibrium between (shown as the first position “a and thesecond position “b” in FIG. 5A) the van der Waals force and mechanicalrestoration force that does not require physical contact between thegraphene membrane and metal trace 503 or metal trace 504. For example,first position “a” could be the “off” state for this particular graphenedrum and second position “b” could be the “on” state.

To read the memory state, a DC voltage can be applied between thegraphene 505 (which is between the oxide 506) and trace 503. The thermalamplitude of the graphene drum 502 (such as in on the order of 1angstrom) will cause an AC tunneling current at a certain frequency thatcan be sensed to determine that a particular graphene drum within a cellis in a given state (“off” in the instance illustrated in FIG. 5A). Tochange the state of the pictured graphene drum from “off” (i.e.,position “a”) to “on” (i.e., position “b”), a DC voltage with an ACvoltage component (with a frequency near the mechanical resonantfrequency of the target graphene-drum) is applied between trace 504 andthe graphene 505. After a short time, the graphene drum 502 will movefrom “off” (i.e., position “a”) to “on” (i.e., position “b”) (whereinposition “b” is another non-contact stable equilibrium position wherevan der Waals forces are balanced with mechanical restoration forces).

An advantage of the embodiment illustrated in FIG. 5A is that nophysical contact is required for any state (thus no mechanical wear).Another advantage is that both the “on” and “off” states can be rapidlyread with a DC voltage and that all the graphene drums within a cell canbe read at the same time. Each graphene drum within a cell will give offan AC tunneling current at a particular frequency that can besensed/differentiated by an external circuit just as radio waves ofdifferent frequencies can be sensed by a single radio receiver.

FIG. 5B depicts another graphene-drum memory chip cell 507. As shown inFIG. 5B, graphene-drum memory chip cell 507 is arranged similar to thegraphene-drum memory chip cell 501 shown in FIG. 5A, in which a thinlayer of oxide 508 (such as an oxide disk) is added to metal trace 504on the side facing graphene drum 502. The thickness of this thin layerof oxide 508 can be around a few angstroms (i.e., around 1 to 3angstroms). On the side of the thin layer of oxide 508 facing thegraphene drum 502 is a layer of metal 509 (such as a metal disk). Thethickness of the layer of metal 509 can be a few nanometers (i.e.,around 1 to 3 nm).

When graphene-drum memory chip cell 507 is read, the graphene membrane502 comes within field emission (FE) or tunneling current range of themetal layer 509 and current flows into the metal layer 509, through theoxide layer 508 and into metal trace 504. Because the effectiveresistance of the oxide layer 508 is high, there will be a large voltagedrop between the metal layer 509 and metal trace 504 when current isflowing, which in turn lowers the electrostatic attraction between thegraphene membrane 502 and the metal layer 509. Again, due to a balancebetween van der Waals forces, electrostatic forces, and mechanicalrestoration forces, the graphene drum 502 will be at a stableequilibrium position near the metal layer that is within FE or tunnelingcurrent range.

A thermal oscillation (or an induced oscillation) of the graphenemembrane will cause an AC FE/tunneling current that has an electricalfrequency equal to the mechanical resonant frequency of graphene drum502. In this position, the graphene drum 502 is considered to be in an“on” state. In cells that have multiple graphene drums, even though thearray of graphene drums within that memory chip cell may have differentmechanical properties (such as stiffness), the graphene drums will eachestablish a precise FE/tunneling distance between themselves and themetal layer due the voltage drop effect described above.

To write the memory element shown in FIG. 5B, an AC voltage (with anelectrical frequency equal to the mechanical resonant frequency ofgraphene drum 502) between V₂ and V₃ is used to force graphene drum 502to mechanically oscillate much more than the other graphene drumsconnected to trace 503 and metal trace 504. Eventually, graphene drum502 will come so close to the metal layer 509 that van der Waals forceswill pull graphene drum 502 into the metal layer 509 and graphene drum502 will “stick” on the metal layer 509. At this point, graphene drum502 cannot mechanically oscillate and will thus be in an “off” state. Toswitch graphene drum 502 back into an “on” state, a voltage V1 on uppergate 503 can be used to pull graphene drum 502 off of the metal layer509 with an electrostatic force and allow it to remain in a free state(where it can be read as described above).

FIG. 5C depicts another graphene-drum memory chip cell 510. As shown inFIG. 5C, graphene-drum memory chip cell 510 is arranged similar to thegraphene-drum memory chip cell 501 shown in FIG. 5B, in which a thinlayer of oxide 511 (such as an oxide disk) is added to trace 503 on theside facing graphene drum 502. Like oxide 508, the thickness of thisthin layer of oxide 511 can also be around a few angstroms (i.e., around1 to 3 angstroms). On the side of the thin layer of oxide 511 facing thegraphene drum 502 is a layer of metal 512 (such as a metal disk). Likemetal layer 509, the thickness of the layer of metal 512 can be a fewnanometers (i.e., around 1 to 3 nm).

Graphene-drum memory chip cell 510 can be used just like graphene-drummemory chip cells 501 and 507, with the benefit that the metal/oxidelayers on traces 503 and 504 allow graphene drum 502 to be read over amuch wider range of voltages and constructed with relaxed tolerances(because the voltage drop across the oxide layers 508 and 511 allows aprecise FE/tunneling gap to be established between graphene drum 502 andthe metal layers 509 and 512, respectively, even if each graphene drumin the cell has significantly different mechanical properties).

FIG. 5D depicts another graphene-drum memory chip cell 513. As shown inFIG. 5D, graphene-drum memory chip cell 513 is arranged similar to thegraphene-drum memory chip cell 501 shown in FIG. 5A, in which thegraphene drum 502 includes small metallic particles 514 (such asmetallic dots) and trace 504 has an array of oxide features 516 on theside facing the graphene drum.

The metallic particles 514 will change the mechanical resonant frequencyof the graphene drum (as discussed above). Furthermore, the metallicparticles will also create an electric field “enhancement factor” thatenables a field emission current (I_(FE)) 515 to flow between graphenedrum 502 and trace 503.

This field emission current can be used to read the memory state ofgraphene drum 502 even when the graphene drum 502 is several nm awayfrom trace 503. This would render the device easier to manufacture thana device that requires 3-10 angstrom tunneling current gaps.

To position the graphene drum 502 in an “off” position, an AC voltagebetween graphene 505 and trace 504 at an electrical frequency close tothe mechanical resonant frequency of graphene drum 502 will put thegraphene drum 502 in contact with an oxide feature 516. Once in contactwith the oxide feature 515, graphene drum 502 will remain in thisposition (i.e., the graphene drum 502 will remain in the “off position”)due to van der Waals forces.

To position the graphene drum 502 in an “on,” a voltage can be appliedbetween trace 503 and graphene drum 502. Once free from the oxidefeature 516, graphene drum 502 will remain in an unstuck position (i.e.,the “on” position). To read a graphene drum in an on position, an ACvoltage between graphene 505 and trace 503 at an electrical frequencyclose to the mechanical resonant frequency of graphene drum 502 will putthe metallic particles 514 on the graphene drum near enough to trace 503to produce a time-varying FE current 515 that can be read/measured. Whena given graphene drum cannot be read through a FE current at a certainAC voltage excitation frequency it can be assumed to be in the offposition (stock on oxide feature 516).

As oriented above for FIG. 5D, first position “a” could be the “on”state for this particular graphene drum 513 and second position “b”could be the “off” state (which is opposite the orientation of “on” and“off” as defined above for FIG. 5A). The “on” and “off” states arepositions relative to one another. A person of skill in the art wouldunderstand that one position can be designated as the “on” position forthe graphene drum in the graphene-drum memory chip cell, and the otherposition as the “off” position (and vice versa).

FIG. 6 depicts how a given graphene drum cell 602 of an assembly 601 canbe chosen by placing a voltage between the graphene of the graphene-drumcell 602 and either trace 604 or trace 605. As with the otherembodiments, the graphene drums 603 within a given graphene-drum cell602 can be individually addressed by exploiting the differences in themechanical resonant frequency of each graphene drum 603 within thetarget graphene-drum cell 602. A purpose for the cross bar assembly asshown in FIG. 6 (graphene oxide assembly 601) is that it allows for theisolation of one graphene-drum cell from the other cells of the assembly601 to limit the number of graphene drums within a given graphene cell.By such isolation, each graphene drum within a given cell can have adistinct resonant frequency without varying the size of each graphenedrum (or the number and/or placement of the metallic balls) too much.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

While embodiments of the invention have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the invention. Theembodiments described and the examples provided herein are exemplaryonly, and are not intended to be limiting. Many variations andmodifications of the invention disclosed herein are possible and arewithin the scope of the invention. For example, the selection tracescould be replaced with an array of conventional silicon switches toaddress individual cells. Accordingly, other embodiments are within thescope of the following claims. The scope of protection is not limited bythe description set out above, but is only limited by the claims whichfollow, that scope including all equivalents of the subject matter ofthe claims.

The disclosures of all patents, patent applications, and publicationscited herein are hereby incorporated herein by reference in theirentirety, to the extent that they provide exemplary, procedural, orother details supplementary to those set forth herein.

1. A memory chip comprising an array of electrically conductive drumsthat have a range of mechanical resonant frequencies that can beindividually addressed with an electrical signal between saidelectrically conductive drums and a nearby electrically conductivemember.
 2. The memory chip of claim 1, wherein the array of electricallyconductive drums is an array of graphene drums.
 3. The memory chip ofclaim 2, wherein the memory chip comprises a layer, wherein the layercomprises the array of graphene drums.
 4. The memory chip of claim 3,wherein the layer comprises a plurality of graphene-drum memory chipcells, wherein each of the graphene-drum memory chip cells comprise atleast one graphene drum of the array of graphene drums.
 5. The memorychip of claim 2, further comprising a selection trace system, wherein(a) the selection trace system comprises a plurality of selectiontraces; and (b) each of the graphene memory chip cells is operablyconnected to a corresponding pair of selection traces in the selectiontraces such that each of the graphene memory chip cells can beindividually selected by selecting the corresponding pair of selectiontraces for the graphene-drum memory chip cell.
 6. The memory chip ofclaim 5, wherein each of the graphene drums in the plurality ofgraphene-drum memory chip cells is operable to be in an “on” positionand an “off” position.
 7. The memory chip of claim 6, further comprisinga contact trace system, wherein (a) the contact trace system comprisesat least one contact trace, (b) a graphene drum in the plurality ofgraphene-drum memory chip cells is in a first position when the graphenedrum is contacting at least one of the contact traces in the contacttrace system; (c) the graphene drum in the plurality of graphene-drummemory chip cells is in a second position when the graphene drum is notcontacting at least one of the contact traces in the contact tracesystem; and (d) the first position and second position are selected fromthe group consisting of (a) the “on” position and the “off” position,respectively, and (b) the “off” position and the “on” position,respectively.
 8. The memory chip of claim 7, further comprising avoltage source and an external circuitry, wherein the voltage source isoperable to apply a voltage such that the external circuitry candetermine whether the graphene drum of the plurality of graphene drummemory chip cells is in the “on” or “off” position.
 9. The memory chipof claim 7, comprising a high voltage source, wherein the high voltagesource that is operable to apply a pulse individually to the graphenedrum in the graphene-drum memory chip cells to switch the graphene drumfrom the “on” position to the “off” position.
 10. The memory chip ofclaim 2, further comprising a trace system, wherein (a) the trace systemcomprises at least a first trace and a second trace; (b) a graphene drumin the plurality of graphene-drum memory chip cells is in the “on”position when the graphene drum is in a stable equilibrium between thevan der Waals forces caused by the first trace and a mechanicalrestoration force; and (c) the graphene drum in the plurality ofgraphene-drum memory chip cells is in the “off” position when thegraphene drum is in a stable equilibrium between the van der Waalsforces caused by the second trace and the mechanical restoration force.11. The memory chip of claim 10, wherein the graphene drum does notcontact the first trace when in the first position, and the graphenedrum does not contact the second trace when in the second position. 12.The memory chip of claim 10, wherein the graphene drum is operable toreceive a voltage such that a thermal amplitude of the graphene drum cancause an AC tunneling current that can be detected to determine whetherthe graphene drum is in the “on” position or the “off” position.
 13. Thememory chip of claim 2, further comprising a trace system having atleast a first trace and a second trace, wherein (a) the first trace isin contact with a first layer of oxide positioned between the firsttrace and the graphene drum; and (b) the first layer of oxide is incontact with a first layer of metal positioned between the first layerof oxide and the graphene drum.
 14. The memory chip of claim 13, wherein(a) a graphene drum in the plurality of graphene-drum memory chip cellsis in a first position when the graphene drum is contacting the firstlayer of metal; (b) the graphene drum in the plurality of graphene-drummemory chip cells is in a second position when the graphene drum is notcontacting the first layer of metal; and (c) the first position andsecond position are selected from the group consisting of (a) the “on”position and the “off” position, respectively, and (b) the “off”position and the “on” position, respectively.
 15. The memory chip ofclaim 13, wherein (a) the second trace is contacted with a second layerof oxide positioned between the second trace and the graphene drum; and(b) the second layer of oxide is contacted with a second layer of metalpositioned between the second layer of oxide and the graphene drum. 16.The memory chip of claim 2, wherein the memory chip has a plurality oflayers, wherein each layer of the plurality layers comprises an array ofgraphene drums.
 17. The memory chip of claim 16, wherein each layer ofthe plurality layers comprises a plurality of graphene-drum memory chipcells, wherein each of the graphene-drum memory chip cells comprise atleast one graphene drum of the array of graphene drums.
 18. The memorychip of claim 1, wherein at least some of the drums in the array ofelectrically conductive drums have particles of material on one side,where the electrically conductive drums that have particles have analtered resonant frequency due to the particles there upon.
 19. Thememory chip of claim 18, wherein the particles of material are balls ofmaterials.
 20. The memory chip of claim 18, wherein the array ofelectrically conductive drums is an array of graphene drums.
 21. Thememory chip of claim 18, wherein the material of the particles comprisesa metal.
 22. The memory chip of claim 18, wherein the particles areparticles of sputtered metal.
 23. The memory chip of claim 18, whereinthe amount of alteration of the resonant frequency of the electricallyconductive drums depends on the number, size, and location of theparticles upon the electrically conductive drums.
 24. The memory chip ofclaim 20, further comprising a trace system having at least a firsttrace and a second trace, wherein the first trace is in contact at leastone non-conductive feature positioned between the first trace and thegraphene drum.
 25. The memory chip of claim 24, wherein thenon-conductive feature is an oxide feature.
 26. The memory chip of claim24, wherein (a) a graphene drum in the plurality of graphene-drum memorychip cells is in a first position when the graphene drum is contactingthe non-conductive feature; (b) the graphene drum in the plurality ofgraphene-drum memory chip cells is in a second position when thegraphene drum is not contacting the non-conductive feature; and (c) thefirst position and second position are selected from the groupconsisting of (a) the “on” position and the “off” position,respectively, and (b) the “off” position and the “on” position,respectively.
 27. The memory chip of claim 26, wherein the particles areoperable for enabling a field emission current to flow between thegraphene drum and the second trace.
 28. A method of reading a memorystate of an electrically conductive drum in an electrically conductivememory chip cell, wherein the electrically conductive drum is operablefor moving between a first position and a second position, the methodcomprising: (a) applying a voltage between the electrically conductivedrum and a nearby electrically conductive member that can cause atunneling current due to the thermal amplitude of the graphene drum; (b)sensing the frequency of the tunneling current; and (c) determiningwhether the electrically conductive drum is in the first position or thesecond position, wherein the first position and second position areselected from the group consisting of (a) the “on” position and the“off” position, respectively, and (b) the “off” position and the “on”position, respectively.
 29. The method of claim 28, wherein theelectrically conductive drum is a graphene drum.
 30. The method of claim28, wherein (a) the electrically conductive drum is contacting theelectrically conductive member when the electrically conductive drum isin the first position; and (b) the electrically conductive drum is notcontacting the electrically conductive member when the electricallyconductive drum is in the second position.
 31. The method of claim 30,wherein the second position is a stable equilibrium position where vander Waals forces are balanced with mechanical restoration forces uponthe electrically conductive drum when positioned at the second position.32. The method of claim 28, wherein (a) the electrically conductive drumis not contacting the electrically conductive member when theelectrically conductive drum is in the first position; and (b) theelectrically conductive drum is not contacting the electricallyconductive member when the electrically conductive drum is in the secondposition.
 33. The method of claim 32, wherein (a) the first position isa first stable equilibrium position where van der Waals forces arebalanced with mechanical restoration forces upon the electricallyconductive drum when positioned at the first position; and (b) thesecond position is another stable equilibrium position where the van derWaals forces are balanced with the mechanical restoration forces uponthe electrically conductive drum when positioned at the second position.34. The method of claim 28, wherein (a) the electrically conductivemember is in contact with a first layer of oxide positioned between theelectrically conductive member and the electrically conductive drum; and(b) the first layer of oxide is in contact with a first layer of metalpositioned between the first layer of oxide and the electricallyconductive drum.
 35. The method of claim 34, wherein (a) theelectrically conductive drum is in the first position when theelectrically conductive drum is contacting the first layer of metal; and(b) the electrically conductive drum in the plurality of graphene-drummemory chip cells is in the second position when the electricallyconductive drum is not contacting the first layer of metal.
 36. Themethod of claim 34, wherein (a) a second electrically conductive membernearby the electrically conductive drum is contacted with a second layerof oxide positioned between the second electrically conductive memberand the electrically conductive drum; and (b) the second layer of oxideis contacted with a second layer of metal positioned between the secondlayer of oxide and the electrically conductive drum.
 37. The method ofclaim 28 further comprising selecting the electrically conductive drumusing a selection trace system operatively connected to the electricallyconductive drum memory chip cell, wherein: (a) the selection tracesystem comprises a plurality of selection traces, and (b) theelectrically conductive drum memory chip cell is operably connected to acorresponding pair of selection traces in the selection traces such thatthe electrically conductive memory chip cell can be individuallyselected by selecting the corresponding pair of selection traces for theelectrically conductive drum memory chip cell.